Scissors jack



June 20, 1967 R. c. JENKINS 3,326,527

SCISSORS JACK Filed July 12. 1966 M/l E/VTOR ROBERT C. JENKINS ATTORNEY United States Patent 3,326,527 SCISSORS JACK Robert C. Jenkins, 585 67th St., West New York, NJ. 07093 Filed July 12, 1966, Ser. No. 564,644 6 Claims. (Cl. 254-122) My invention relates to motor vehicle jacks generally and specifically to a pump action scissors jack.

A wide variety of motor vehicle jacks are known of the scissors type employing What are commonly known as lazy tongs which are pivoted together. Most scissors jacks are purely mechanical in operation and rely upon an actuating lever or bar which is rotated which in turn rotates a pinion gear. Frictional losses are so enormous that great force must be exerted to rotate the actuating rod. Moreover, it is basically difficult to exert large forces on a rotatable member secured at only one end.

Hydraulic scissors jacks have been proposed but these jacks are excessively complex and costly and in many instances rely upon the rotation of an actuating lever.

As a result of these difiiculties, the scissors jack has given way in recent years to the mechanical bumper jack except for the large hydraulically operated piston jacks found in automotive garages. The bumper jack, however, comprising either one or three generally vertical members with a hook adapted to ride mechanically up and down one member are notoriously unstable. However, their popularity is based largely on the fact that they are actuated by a lever which is pumped up and down. Such up and down pivotal motion is easy to apply and great forces may be exerted with minimal physical efiort.

While some hydraulic bumper jacks have been proposed, most of them are extremely slow in operation, the movement of the bumper hook being very slight for each pump cycle. In addition, the total elongation of the hydraulic bumper jack is limited unless reservoirs of relatively large quantities of fluid are provided.

Therefore, there is great need for a bumper jack which is actuated by pumping a handle in the vertical plane which has relatively low frictional losses, which has a relatively large and rapid expansion with suflicient mechanical advantage to lift the car and which can provide a relatively large flat base which is stable against upset. My proposed scissors jack meets these desiderata.

Therefore, it is among the objects and advantages of my invention to provide a scissors jack which is operated by a lever which is pumped up and down in a generally vertical plane.

Another object of my invention is to provide a scissors jack in which a relatively few cycles of the actuating lever produce a relatively large vertical excursion of the lazy tongs with sufficient mechanical advantage to lift the vehicle without the exertion of undue force on the lever.

A further object of my invention is to provide a scissors jack which is preferably actuated by hydraulic fluid but which may be actuated by a mechanical linkage or a combination of a mechanical linkage and a hydraulic fluid.

Still another object of my invention is to provide a scissors jack in which a pair of opposed, arcuate rack of gears mesh with a pair of pivotal tong actuating members to raise and lower the lazy tongs.

Still yet another object of my invention is to provide a scissors jack in which a pair of arcuate rack gears are driven in opposite directions by a pair of opposed pistons in a hydraulic cylinder.

Yet a further object of my invention is to provide a scissors jack in which a tilting member secured to the uppermost tongs is provided with means to engage a bumper of a motor vehicle.

These objects and advantages as well as other objects and advantages may be achieved by my invention, one embodiment of which is illustrated in the drawings in which:

FIGURE 1 is a side elevational view of my scissors jack with one vertical support member removed;

FIGURE 2 is a side elevational view of my scissors jack fully extended in the vertical direction and showing the hydraulic actuating system;

FIGURE 3 is an end elevational, cross-sectional view of my scissors jack taken along line 33 in FIGURE 1 looking in the direction of the arrows;

FIGURE 4 is a schematic view of my hydraulic actuating system.

Referring now to the drawings in detail, my scissors jack comprises a flat, generally rectangular base 11 which is dimensioned not only to accommodate the accessory parts mounted thereon but sutficiently large to provide a stable platform for the vehicle When the said vehicles weight is resting thereon. A pair of generally vertical spaced apart supports 12 and 13 are rigidly mounted on the base 11 on its top and generally perpendicular thereto. A pair of lazy tongs 14 and 15 are pivotally engaged to the supports 12 and 13 by means of a transverse pin 16. The tongs 14 and 15 are pivotally engaged at their opposite ends to a second pair of tongs 17 and 18. Tongs 17 and 18 cross and are pivotally engaged to each other generally at their mid-point by pin 19. The upper or opposite ends of tongs 17 and 18 are pivotally engaged to tongs 2t) and 21 respectively. The tongs 14, 15, 17, 18 and 20, 21 and their pivotal interengagement as Well as their pivotal mount on pin 16 are well known and in and of themselves do not constitute any part of the present invention.

A hydraulic cylinder 22 is mounted horizontally on top of the base 11 symmetrically beneath pin 16 and lies generally in the plane of the tongs 14, 15, 17, 18, and 21. A pair of opposed pistons 23 and 24 are mounted in the cylinder 22 in opposition to each other. A conduit 25 connects with the hydraulic cylinder 22 at its midpoint, the opposite end of conduit 25 being connected to a source of hydraulic fluid under pressure.

Pistons 23 and 24 are provided with connecting rods 26 and 27 respectively which extend in opposite directions beyond the respective ends of the cylinder 22. The ends of the connecting rods 26 and 27 opposite pistons 23 and 24 connect respectively to an arcuate rack gear respectively 28 and 29.

Each rack gear 28 and 29 comprises a flat base respectively 30 and 31 which is supported by and rides upon the top of the base 11 of the assemblage.

The opposite or top edge of the rack gears 28 and 29 are each provided with a series of gear teeth 32 which are oriented in a generally arcuate configuration. In addition, each rack gear 28 and 29 is provided with a flat, upstanding, generally vertical end edge 33 opposite the connecting rod 26 or 27.

The rack gears 28 and 29 are meshed respectively with pivotal actuating members 34 and 35. Each actuating member 34 and 35 is pivotally mounted to the supports 12 and 13 by pins 36 and 37 respectively. Each rack gear 28 and 29 is provided with gear teeth 38 along a portion of its bottom edge which are meshed with the gear teeth 32 of the respective rack gears 28 and 29. In addition, each actuating member is provided with a generally vertically depending leg, respectively 39 and 40 which are in engagement with the end edge 33 of the respective rack gear 28 or 29 when the lazy tongs are in their lowermost position.

Each actuating member 34 and 35 is provided with a straight contact edge 41 and 42 respectively. The contact edges 41 and 42 are always in contact with tongs 14 and respectively. The tongs 14 and 15 and the actuating members 34 and 35 as well as rack gears 28 and 29 and cylinder 22 are dimensioned and interpositioned so that contact edges 41 and 42 are generally parallel to the bottom edge of tongs 14 and 15 respectively when the jack is in its lowermost position. At that time, the rack gears 28 and 29 are in their closest position as determined by the extent of inward excursion of pistons 23 and 24. In this position, depending legs 39 and 40 of the actuating members 34 and 35 respectively are in engagement with the end edge 33, 33 of the rack gears 28 and 29. Thus, the weight of the vehicle if then resting on the jack is distributed over a relatively large surface area comprising not only the surface of contact edges 41 and 42 but also the legs 39 and 40 and teeth 32 and 38. Such an arrangement prevents accidental damage to the actuating mechanism generally in the event that the Vehicle descends downwardly to collapse the jack to the fullest. If the design were otherwise, the full weight of the vehicle might well be transmitted to pins 16 and 19. Moreover, tongs 17 and 18 are provided with enlargements 43 and 44 on their top edge which engage tongs 20 and 21 respectively when the jack is in its lowermost or most collapsed position. This tends to distribute the weight incident upon the jack more evenly.

The essence of my invention lies in the hydraulic cylinder 22, pistons 23 and 24, connecting rods 26 and 27, and rack gears 28 and 29 in contact with tongs 14 and 15. As may be seen in FIGURE 2; when hydraulic fluid is forced through conduit into cylinder 22 between the pistons 23 and 24, the pistons 23 and 24 are forced apart, propelling the rack gears 28 and 29 respectively in opposite directions away from the cylinder 22 along the base 11. Since the rack gears 28 and 29 are in meshed engagement with the pivotal actuating members 34 and 35 respectively, the said members rotate about pins 36 and 37, member 34 rotating in a clockwise direction and member 35 rotating in a counterclockwise direction. Since tongs 14 and 15 are pivotally engaged about pin 16, their included angle decreases and their ends converge. Convergence of the ends of tongs 14 and 15 produces corresponding convergence of the ends of tongs 17 and 18 and total upward excursion of the said tongs in a direction parallel to their plane and perpendicular to the plane of the base 11. Release of the hydraulic pressure within cylinder 22 permits weight incident upon the jack assemblage to force the tong downwardly rotating the pivotal actuating members 34 and 35 now in an opposite direction and forcing rack gears 28 and 29 inwardly toward each other and the hydraulic cylinder 22.

As a collateral aspect of invention, the top most tongs 20 and 21 are each pivotally connected to a bumper support member 45 which may be provided with a V-shaped cut 46 to receive and nest the bumper. The double pivotal connection of bumper support 45 permits limited movement of bumper 45 to accommodate the bumper. At the same time, a single pivot point is avoided which would permit too far an excursion of the degree of pivotability of member 45.

Any convenient means may be employed to generate hydraulic pressure within cylinder 22. In the embodiment of my invention illustrated in the drawings, I have shown a simple hydraulic pump system. The system comprises a hydraulic cylinder 47 with a piston 48 mounted therein. The cylinder 47 is mounted in a vertical plane as is piston 48. The end of the piston 48 opposite the cylinder 47 is pivotally connected to an actuating arm 49. The end of arm 49 is pivotally connected to a stanchion 50. Thus, vertical reciprocatory movement of the actuating arm or lever 49 in the vertical plane causes the piston 48 to rise and fall in the cylinder 47. V

The bottom of the cylinder is provided with a pair of unidirection valves 51 and 52 respectively. Valve 51 is connected to T conduit 53. One leg of T conduit 53 is connected to conduit 25, the opposite leg of T 53 being connected to a valve 54.

Valve 52 at the bottom of cylinder 47 is connected through conduit 55 to a hydraulic fluid reservoir 56. The reservoir 56 is connected through conduit 57 to the side of valve 54 opposite T conduit 53.

Pressure within cylinder 47 opens valves 51 permitting fluid to flow through T conduit 53. If valve 54 is closed, fluid flows through conduit 25 into the hydraulic cylinder 22. Valve 52 closes when pressure is generated within cylinder 47, if said pressure is greater than the pressure in reservoir 56. Thus, if valve 54 is closed and lever 49 is pumped, fluid is forced under pressure into cylinder 22.

Additional fluid is drawn on each stroke of piston 48 from reservoir 56.

In order to lower the jack, valve 54 opens permitting fluid to pass rearwardly from cylinder 22 through conduit 25, T 53 and conduit 57 back into the reservoir 56.

While I have illustrated one relatively simple type of hydraulic pressure generating means, any number of means may be employed and said means may be mechanical in nature as distinguished from the pure hydraulic pump system illustrated. The particular means for generating the hydraulic fluid in and of itself does not comprise a any part of my invention.

The foregoing description is merely intended to illustrate an embodiment of the invention. The component parts have been shown and described. They each may have substitutes which may perform a substantially similar function; such substitutes may be known as proper substitutes for the said components and may have actually been known or invented before the present invention; these substitutes are contemplated as being within the scope of the appended claims, although they are not specifically catalogued herein.

I claim:

1. A scissors jack comprising:

(a) a base,

(b) an upstanding support on the base,

(0) a first pair of tongs pivotally mounted to the support,

(d) a pair of rack gears slidably mounted on the base,

(e) means for forcibly moving the rack gears in opposite directions along the base,

(f) a pair of gear actuating members pivotally mounted to the support, each said member engageable respectively with one of the said first pair of tongs upon pivotal movement,

(g) each actuating member being in meshed engagement respectively with one of the racked gears, the actuating members pivoting upon movement of the rack gear to which it is engaged, and,

(h) a plurality of crossed tongs pivotally engaged to the first said pair of tongs and interengaged at their uppermost ends.

2. A scissors jack comprising:

(a) the structure in accordance with claim 1 in which,

(b) the means for forcibly moving the rack gears are,

(c) a hydraulic cylinder positioned between the rack gears,

(d) a pair of pistons slidably mounted in the cylinder, the end of each piston respectively extending beyond one end of the cylinder and connected to a rack gear,

(e) means for introducing hydraulic fluid under pressure into the cylinder between the pistons and (f) means for withdrawing said hydraulic fluid from the cylinder.

3. A scissors jack comprising:

(a) the structure in accordance with claim 1 in which,

(b) the ends of the gears on each rack gear are disposed along an arc, and

(c) the ends of the gears on each actuating member are disposed along an arc.

4. A scissors jack comprising: (b) an upstanding edge on each rack gear opposite the (a) the structure in accordance with claim 2 in which, piston to which it is connected and,

(b) the ends of the gears on each rack gear are dis- (0) a depending leg on each actuating member engageposed along an arc, and able with the said upstanding edge of the rack gear (0) the ends of the gears on each actuating member 5 with which it is meshed.

are disposed along an arc.

5. A scissors jack comprising:

(a) the structure in accordance with claim 1, and

(b) a pair of uppermost, non-intersecting tongs pivotally connected respectively to the uppermost ends of the uppermost crossed tongs, and

(c) a support member pivotally connected to the end of each of the non-intersecting tongs opposite the crossed tongs, at spaced apart pivot points.

6. A scissors jack comprising:

(a) the structure in accordance with claim 1 and,

References Cited UNITED STATES PATENTS 1,701,314 2/1929 Shook 254-126 10 2,580,829 1/1952 Peck 254-122 FOREIGN PATENTS 102,666 10/1963 Norway.

15 OTHELL M. SIMPSON, Primary Examiner. 

1. A SCISSORS JACK COMPRISING: (A) A BASE, (B) AN UPSTANDING SUPPORT ON THE BASE, (C) A FIRST PAIR OF TONGS PIVOTALLY MOUNTED TO THE SUPPORT, (D) A PAIR OF RACK GEARS SLIDABLY MOUNTED ON THE BASE, (E) MEANS FOR FORCIBLY MOVING THE RACK GEARS IN OPPOSIVE DIRECTIONS ALONG THE BASE, (F) A PAIR OF GEAR ACTUATING MEMBERS PIVOTALLY MOUNTED TO THE SUPPORT, EACH SAID MEMBER ENGAGEABLE RESPECTIVELY WITH ONE OF THE SAID FIRST PAIR OF TONGS UPON PIVOTAL MOVEMENT, 